Oracle 11g队列锁等待事件解释

发布时间：2020-12-12 16:32:07 所属栏目：百科来源：网络整理

导读：有时候看到数据库报告中的enq:xxx不知道什么意思，现在列出来以供参考。 enq: AD – allocate AU Synchronizes accesses to a specific OSM disk AU enq: AD – deallocate AU Synchronizes accesses to a specific OSM disk AU enq: AF – task serializati

enq: AD – allocate AUSynchronizes accesses to a specific OSM disk AUenq: AD – deallocate AUSynchronizes accesses to a specific OSM disk AUenq: AF – task serializationThis enqueue is used to serialize access to an advisor taskenq: AG – contentionSynchronizes generation use of a particular workspaceenq: AO – contentionSynchronizes access to objects and scalar variablesenq: AS – contentionSynchronizes new service activationenq: AT – contentionSerializes ‘alter tablespace’ operationsenq: AW – AW$ table lockGlobal access synchronization to the AW$ tableenq: AW – AW generation lockIn-use generation state for a particular workspaceenq: AW – user access for AWSynchronizes user accesses to a particular workspaceenq: AW – AW state lockRow lock synchronization for the AW$ tableenq: BR – file shrinkLock held to prevent file from decreasing in physical size during RMAN backupenq: BR – proxy-copyLock held to allow cleanup from backup mode during an RMAN proxy-copy backupenq: CF – contentionSynchronizes accesses to the controlfileenq: CI – contentionCoordinates cross-instance function invocationsenq: CL – drop labelSynchronizes accesses to label cache when dropping a labelenq: CL – compare labelsSynchronizes accesses to label cache for label comparisonenq: CM – gateSerialize access to instance enqueueenq: CM – instanceIndicate OSM disk group is mountedenq: CT – global space managementLock held during change tracking space management operations that affect the entire change tracking fileenq: CT – stateLock held while enabling or disabling change tracking,to ensure that it is only enabled or disabled by one user at a timeenq: CT – state change gate 2Lock held while enabling or disabling change tracking in RACenq: CT – readingLock held to ensure that change tracking data remains in existence until a reader is done with itenq: CT – CTWR process start/stopLock held to ensure that only one CTWR process is started in a single instanceenq: CT – state change gate 1Lock held while enabling or disabling change tracking in RACenq: CT – change stream ownershipLock held by one instance while change tracking is enabled,to guarantee access to thread-specific resourcesenq: CT – local space managementLock held during change tracking space management operations that affect just the data for one threadenq: CU – contentionRecovers cursors in case of death while compilingenq: DB – contentionSynchronizes modification of database wide supplemental logging attributesenq: DD – contentionSynchronizes local accesses to ASM disk groupsenq: DF – contentionEnqueue held by foreground or DBWR when a datafile is brought online in RACenq: DG – contentionSynchronizes accesses to ASM disk groupsenq: DL – contentionLock to prevent index DDL during direct loadenq: DM – contentionEnqueue held by foreground or DBWR to synchronize database mount/open with other operationsenq: DN – contentionSerializes group number generationsenq: DP – contentionSynchronizes access to LDAP parametersenq: DR – contentionSerializes the active distributed recovery operationenq: DS – contentionPrevents a database suspend during LMON reconfigurationenq: DT – contentionSerializes changing the default temporary table space and user creationenq: DV – contentionSynchronizes access to lower-version Diana (PL/SQL intermediate representation)enq: DX – contentionSerializes tightly coupled distributed transaction branchesenq: FA – access fileSynchronizes accesses to open ASM filesenq: FB – contentionEnsures that only one process can format data blocks in auto segment space managed tablespacesenq: FC – open an ACD threadLGWR opens an ACD threadenq: FC – recover an ACD threadSMON recovers an ACD threadenq: FD – Marker generationSynchronizationenq: FD – Flashback coordinatorSynchronizationenq: FD – Tablespace flashback on/offSynchronizationenq: FD – Flashback on/offSynchronizationenq: FG – serialize ACD relocateOnly 1 process in the cluster may do ACD relocation in a disk groupenq: FG – LGWR redo generation enq raceResolve race condition to acquire Disk Group Redo Generation Enqueueenq: FG – FG redo generation enq raceResolve race condition to acquire Disk Group Redo Generation Enqueueenq: FL – Flashback database logSynchronizationenq: FL – Flashback db commandEnqueue used to synchronize Flashback Database and deletion of flashback logs.enq: FM – contentionSynchronizes access to global file mapping stateenq: FR – contentionBegin recovery of disk groupenq: FS – contentionEnqueue used to synchronize recovery and file operations or synchronize dictionary checkenq: FT – allow LGWR writesAllow LGWR to generate redo in this threadenq: FT – disable LGWR writesPrevent LGWR from generating redo in this threadenq: FU – contentionThis enqueue is used to serialize the capture of the DB Feature,Usage and High Water Mark Statisticsenq: HD – contentionSerializes accesses to ASM SGA data structuresenq: HP – contentionSynchronizes accesses to queue pagesenq: HQ – contentionSynchronizes the creation of new queue IDsenq: HV – contentionLock used to broker the high water mark during parallel insertsenq: HW – contentionLock used to broker the high water mark during parallel insertsenq: IA – contentionenq: ID – contentionLock held to prevent other processes from performing controlfile transaction while NID is runningenq: IL – contentionSynchronizes accesses to internal label data structuresenq: IM – contention for blrSerializes block recovery for IMU txnenq: IR – contentionSynchronizes instance recoveryenq: IR – contention2Synchronizes parallel instance recovery and shutdown immediateenq: IS – contentionEnqueue used to synchronize instance state changesenq: IT – contentionSynchronizes accesses to a temp object’s metadataenq: JD – contentionSynchronizes dates between job queue coordinator and slave processesenq: JI – contentionLock held during materialized view operations (like refresh,alter) to prevent concurrent operations on the same materialized viewenq: JQ – contentionLock to prevent multiple instances from running a single jobenq: JS – contentionSynchronizes accesses to the job cacheenq: JS – coord post lockLock for coordinator postingenq: JS – global wdw lockLock acquired when doing wdw ddlenq: JS – job chain evaluate lockLock when job chain evaluated for steps to createenq: JS – q mem clnup lckLock obtained when cleaning up q memoryenq: JS – slave enq get lock2Get run info locks before slv objgetenq: JS – slave enq get lock1Slave locks exec pre to sess strtenq: JS – running job cnt lock3Lock to set running job count epostenq: JS – running job cnt lock2Lock to set running job count epreenq: JS – running job cnt lockLock to get running job countenq: JS – coord rcv lockLock when coord receives msgenq: JS – queue lockLock on internal scheduler queueenq: JS – job run lock – synchronizeLock to prevent job from running elsewhereenq: JS – job recov lockLock to recover jobs running on crashed RAC instenq: KK – contextLock held by open redo thread,used by other instances to force a log switchenq: KM – contentionSynchronizes various Resource Manager operationsenq: KP – contentionSynchronizes kupp process startupenq: KT – contentionSynchronizes accesses to the current Resource Manager planenq: MD – contentionLock held during materialized view log DDL statementsenq: MH – contentionLock used for recovery when setting Mail Host for AQ e-mail notificationsenq: ML – contentionLock used for recovery when setting Mail Port for AQ e-mail notificationsenq: MN – contentionSynchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner sessionenq: MR – contentionLock used to coordinate media recovery with other uses of datafilesenq: MS – contentionLock held during materialized view refresh to setup MV logenq: MW – contentionThis enqueue is used to serialize the calibration of the manageability schedules with the Maintenance Windowenq: OC – contentionSynchronizes write accesses to the outline cacheenq: OL – contentionSynchronizes accesses to a particular outline nameenq: OQ – xsoqhiAllocSynchronizes access to olapi history allocationenq: OQ – xsoqhiCloseSynchronizes access to olapi history closingenq: OQ – xsoqhistrecbSynchronizes access to olapi history globalsenq: OQ – xsoqhiFlushSynchronizes access to olapi history flushingenq: OQ – xsoq*histrecbSynchronizes access to olapi history parameter CBenq: PD – contentionPrevents others from updating the same propertyenq: PE – contentionSynchronizes system parameter updatesenq: PF – contentionSynchronizes accesses to the password fileenq: PG – contentionSynchronizes global system parameter updatesenq: PH – contentionLock used for recovery when setting Proxy for AQ HTTP notificationsenq: PI – contentionCommunicates remote Parallel Execution Server Process creation statusenq: PL – contentionCoordinates plug-in operation of transportable tablespacesenq: PR – contentionSynchronizes process startupenq: PS – contentionParallel Execution Server Process reservation and synchronizationenq: PT – contentionSynchronizes access to ASM PST metadataenq: PV – syncstartSynchronizes slave start shutdownenq: PV – syncshutSynchronizes instance shutdown_slvstartenq: PW – perwarm status in dbw0DBWR 0 holds enqueue indicating prewarmed buffers present in cacheenq: PW – flush prewarm buffersDirect Load needs to flush pre-warmed buffers if DBWR 0 holds enqueueenq: RB – contentionSerializes OSM rollback recovery operationsenq: RF – synch: per-SGA Broker metadataEnsures r/w atomicity of DG configuration metadata per unique SGAenq: RF – synchronization: critical aiSynchronizes critical apply instance among primary instancesenq: RF – new AISynchronizes selection of the new apply instanceenq: RF – synchronization: chiefAnoints 1 instance’s DMON as chief to other instances’ DMONsenq: RF – synchronization: HC masterAnoints 1 instance’s DMON as health check masterenq: RF – synchronization: aifo masterSynchronizes apply instance failure detection and fail over operationenq: RF – atomicityEnsures atomicity of log transport setupenq: RN – contentionCoordinates nab computations of online logs during recoveryenq: RO – contentionCoordinates flushing of multiple objectsenq: RO – fast object reuseCoordinates fast object reuseenq: RP – contentionEnqueue held when resilvering is needed or when data block is repaired from mirrorenq: RS – file deleteLock held to prevent file from accessing during space reclamationenq: RS – persist alert levelLock held to make alert level persistentenq: RS – write alert levelLock held to write alert levelenq: RS – read alert levelLock held to read alert levelenq: RS – prevent aging list updateLock held to prevent aging list updateenq: RS – record reuseLock held to prevent file from accessing while reusing circular recordenq: RS – prevent file deleteLock held to prevent deleting file to reclaim spaceenq: RT – contentionThread locks held by LGWR,DBW0,and RVWR to indicate mounted or open statusenq: SB – contentionSynchronizes Logical Standby metadata operationsenq: SF – contentionLock used for recovery when setting Sender for AQ e-mail notificationsenq: SH – contentionShould seldom see this contention as this Enqueue is always acquired in no-wait modeenq: SI – contentionPrevents multiple streams table instantiationsenq: SK – contentionSerialize shrink of a segmentenq: SQ – contentionLock to ensure that only one process can replenish the sequence cacheenq: SR – contentionCoordinates replication / streams operationsenq: SS – contentionEnsures that sort segments created during parallel DML operations aren’t prematurely cleaned upenq: ST – contentionSynchronizes space management activities in dictionary-managed tablespacesenq: SU – contentionSerializes access to SaveUndo Segmentenq: SW – contentionCoordinates the ‘alter system suspend’ operationenq: TA – contentionSerializes operations on undo segments and undo tablespacesenq: TB – SQL Tuning Base Cache UpdateSynchronizes writes to the SQL Tuning Base Existence Cacheenq: TB – SQL Tuning Base Cache LoadSynchronizes writes to the SQL Tuning Base Existence Cacheenq: TC – contentionLock held to guarantee uniqueness of a tablespace checkpointenq: TC – contention2Lock of setup of a unique tablespace checkpoint in null modeenq: TD – KTF dump entriesKTF dumping time/scn mappings in SMON_SCN_TIME tableenq: TE – KTF broadcastKTF broadcastingenq: TF – contentionSerializes dropping of a temporary fileenq: TL – contentionSerializes threshold log table read and updateenq: TM – contentionSynchronizes accesses to an objectenq: TO – contentionSynchronizes DDL and DML operations on a temp objectenq: TQ – TM contentionTM access to the queue tableenq: TQ – DDL contentionTM access to the queue tableenq: TQ – INI contentionTM access to the queue tableenq: TS – contentionSerializes accesses to temp segmentsenq: TT – contentionSerializes DDL operations on tablespacesenq: TW – contentionLock held by one instance to wait for transactions on all instances to finishenq: TX – contentionLock held by a transaction to allow other transactions to wait for itenq: TX – row lock contentionLock held on a particular row by a transaction to prevent other transactions from modifying itenq: TX – allocate ITL entryAllocating an ITL entry in order to begin a transactionenq: TX – index contentionLock held on an index during a split to prevent other operations on itenq: UL – contentionLock used by user applicationsenq: US – contentionLock held to perform DDL on the undo segmentenq: WA – contentionLock used for recovery when setting Watermark for memory usage in AQ notificationsenq: WF – contentionThis enqueue is used to serialize the flushing of snapshotsenq: WL – contentionCoordinates access to redo log files and archive logsenq: WP – contentionThis enqueue handles concurrency between purging and baselinesenq: XH – contentionLock used for recovery when setting No Proxy Domains for AQ HTTP notificationsenq: XR – quiesce databaseLock held during database quiesceenq: XR – database force loggingLock held during database force logging modeenq: XY – contentionLock used for internal testing顶0踩

（编辑：李大同）

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有时候看到数据库报告中的enq:xxx不知道什么意思，现在列出来以供参考。